In recent years, computerization of cars has been advanced, and the opportunities of using a capacitor in a vehicle onboard device are increasing. The capacitor is connected to a bus bar of a substrate or a module, of the vehicle onboard device via a lead terminal for a capacitor. In the vehicle onboard device, vibration from road and vibration due to rotation of an engine and the like, etc. during driving is continuously applied to the module or the substrate. Consequently, the continuous vibration is applied also to the capacitor implemented on the module and the substrate. As a result, a trouble such as breakage of the lead terminal for a capacitor may occur.
FIG. 10 illustrates the structure of a conventional lead terminal for a capacitor.
The lead terminal 5 for a capacitor is composed of an aluminum wire 2 and a metal wire 3, and the aluminum wire 2 and the metal wire 3 are connected by arc welding or the like. Furthermore, the aluminum wire 2 has a round bar portion 2a having a substantially cylindrical shape, and a flat portion 2b formed by subjecting the round bar portion 2a to a press working or the like, and an inclined portion 2d with a thickness that linearly decreases to the thickness of the flat portion 2b is formed on the flat portion 2b side of the round bar portion 2a. Furthermore, to the flat portion 2b, an electrode foil (not illustrated) of a capacitor element is connected.
A mechanism leading to a breakage due to the stress caused by vibration when the lead terminal 5 for a capacitor having the above structure is used for an electrolytic capacitor will be described with reference to FIG. 11.
As illustrated in FIG. 11, the electrolytic capacitor 10 is formed by housing, together with electrolyte solution for driving, a capacitor element 9 in a cylindrical outer case having a bottom, and sealing an opening formed on the outer casing with sealing body 8, where the capacitor element 9 is configured by winding or laminating electrode foils, which are positive electrode and negative electrode formed of aluminum or the like, with a separator interposed therebetween. Furthermore, in the electrolytic capacitor 10, two lead terminals 5 for capacitor are inserted into respective through holes of a substrate 6, and fixed to the substrate 6 with solder 7 from the back surface of the substrate 6.
Furthermore, in the module, the lead terminal 5 for a capacitor is electrically connected to other electronic components or the like by connecting the lead terminal 5 for a capacitor to the bus bar.
When the substrate 6 is vibrated in the directions of the arrows F parallel to the substrate surface, since the metal wire 3 of the lead terminal 5 for a capacitor is fixed to the substrate 6 with the solder 7, the metal wire 3 vibrates in the directions of the arrows F in a same manner. Consequently, the round bar portion 2a of the aluminum wire 2 connected to the metal wire 3 by arc welding or the like also vibrates in the directions of the arrows F in a same manner. Therefore, the flat portion 2b of the aluminum wire 2 connected to the electrode foils of the capacitor element 9 vibrates in the directions of arrow f from a boundary portion 2e between the round bar portion 2a and the flat portion 2b as a starting point.
As a result, the boundary portion 2e that becomes the starting point of the vibration is alternately intensively subjected to tensile stress and compressive stress as bending moment, which may cause metallic fatigue in the case of continuous vibration, causing breakage of the boundary portion 2e. 
As a capacitor with excellent vibration resistance to such vibration, a structure having increased adhesiveness between the sealing body 8 for sealing openings of the case of the capacitor and the capacitor element 9 is increased to prevent movement of the capacitor element 9 has been suggested. See, for example, JP 2009-277748 A (Patent Literature 1). Furthermore, a suggestion to suppress the vibration of the capacitor itself by providing a projection piece between the sealing body 8 and the substrate 6 has also been made. See, for example, JP 2003-257799 A (Patent Literature 2).
However, vibration resistance is still insufficient in such proposals, and further improvement of vibration resistance has been desired. Furthermore, since such suggestions prevent vibration by making a structural change to the capacitor element, the existing facility used for manufacture are needed to be changed, also increasing cost disadvantageously.